The effect of fires on the llashover voltage of power lines has been investigated in Brazil, Mexico, Canada, USA, South Africa, Australia and Poland. The flashover voltage of outdoor insulation is reduced by hot air, conductive flame and colloidal smoke. The paper explains shortly the fire induced flashovers of air gaps. The safety aspect for firemen and other people caused by step potentials at the arcing point was described. The published works about deterioration of aluminum stranded conductors steel reinforced (ACSR) and detection of fire induced corona are briefly reported.